Master clock



y 1934. G. LOWKRANTZ 1,957,178

MASTER CLOCK Filed March 28, 1932 2 Shee cs-Sheer. 1

INVENTOR E BY ATTORNEY May 1, 1934.

25 5 25 f LfM/h/asf LfM/h. s/ow G. LOWKRANTZ 1,957,178

MASTER CLOCK Filed March 28, 1932 2 Sheets-Sheet 2 On time 8Y A'ITORNEY LOG enema May .1934 I 1,957,178

umrap s'rArEs PATENT: orrica MASTER CIDCK Gunne Lowkrants, Endicott, N. Y., assignor, by mesne assignments, to International Business Machines Corporation, New York,-N. Y., a corporation of New York Application March as, 1932, Serial no. 601,411

2 Claims. 58-25) This invention relates to improvements in elecimpulses, but the A wire continuesto transmit tric clock systems and more particularly to desuch impulses. f vices used in connection with such systems for Each secondary clockis provided with switchinitiating electrical impulses. ing mechanism so that it automatically connects One of the objects of the invention is to proits stepping magnet to the B wire on registering on vide a device for initiating electrical impulses over the fifty-ninth minute and some time later, usua circuit from a timing mechanism without physally when it registersxthirty-minutes alter the ical contact being made between the timing mechhour, disconnects its magnet from the 3 wire and anism and circuit. connects it to the A wire.

Another object is to provide an electric impulse Any secondary clock which remains in step 5 making device on a clock which will cause no adwith the master clock receives a stepp n impulse verse time keeping action in the clock. each minute as it is connected to A wire during A still further object is to provide a condenser the normal synchronizing period and is shiited operable by a clock mechanism for controlling to the B wire only on the fifty-ninth minute in 1 electrical impulses in a circuit of which said conreadiness to receive the first stepping impulse 7o denser is a part. over this wire on the sixtieth minute.

Other objects and advantages of this inven- When a secondary clock is fast it automatically tion will be apparent from the specifications and shifts its stepping magnet to the B wire on reachthe accompanying drawings which show one eming its fifty-ninth minute registration and, as

' go bodiment of this invention. I the B wire is out of circuit during the synchroniz- 7 The invention contemplates the use of a coning period, the fast secondary will receive no more denser controlled by a moving part of a clock stepping impulses during the period. But it will mechanism which will control the current outagain start in step with the master clock when put in a circuit to energize a relay periodically the B wire transmits its next stepping impulse in order to initiate electrical impulses from the on the sixtieth minute. closing of said relay. Heretofore relays operated Secondary clocks which are slow are synchrotrom clock mechanisms have been controlled by nized by a series of rapid impulses transmitted contacts which are closed and opened by physical over the A wire between the fifty-ninth and contact with a moving member of the clock, such sixtieth minutes. The stepping magnet of a 30 as contacts controlled by cams geared to the esslow, secondary. which is connected to the A cape mechanism, from contacts-on tlfilescapewire until it registers fifty-nine minutes, rement wheel shaft and verge shaft, and from conceives these rapid impulses and advances at tacts 0 the pendulum Sweeping t g m each impulse until it reaches the fifty-ninth cury b ths and th r num r s f rm In th minute when it automatically shifts to the B as preferred embodiment the invention s Shown wire in readiness to receive the sixtieth minute initiating impulses once each second and is thereimpulse over this wire causing the secondary f e Operated y a 60 beat Pendulum- For to start off in step with the master clock. treme accuracy it is essential therefore to pro- The invention as applied to a system of this .hib t the Pendulum from making y P y nature is illustrated in the accompanying draw- 40 contact during its swing which would in any way ings in whi h retard or effect its period Of oscillation. Fig 1 is a, front view of a, master clock and The invention is applicable to diflerent types pendulum with its a so iat d d r; of electrical impulse clock systems but in order Fig, 2 shows a, front elevation of the method to clearly visualize its advantages it will be de of mounting a, 3 plate condenser ith l ti 45 scribed as applied to a self-synchronizing system t t pendulum;" as illustrated and described in U. S. patent to Fig 3 1 id l ti f th mounting in J. W. Bryce. #1,687,491, dated October 16, 1928. pm The system in that patent transmits minute stepi 4 i wiring diagram f an hourly 5w P impulses during normal operating Periods pervised clock system and an amplifier circuit 50 fr the master clock 0V9! either of two Wires, connected thereto and controlled by the master usually designated as the A and B wires, respecl I tively. During a synchronizing period in each Fig. 5 is a graphic representation showing th hour, ordinarily lasting from the forty-fourth to' r lt t current conditions in t plate the fifty-ninth minute, the 13 wire is cutout of out;

55 circuit so that it transmits no minute stepping Fig. 6 is a graphic representation showing the relation of the plate current to the grid potential.

Referring first'to Fig. 4 a source of current is indicated at ss. A master clock drives a series of cams which control contacts to trans-- mit impulses over wires A and B and to control the switching of the wire B out of circuit during the synchronizing period. Contacts 10 are closed once each minute to'control the minute stepping impulses. These impulses (through wires 11 and 12, contact 10, relay coil 13 and wire 14) energize relay coil 13 once each minute causing it to close its contacts 15 to supply minute stepping impulses from the source S to the A and B wires.

The stepping impulses are supplied to the A wire constantly as this wire is connected directly to relay contacts 15. The stepping impulses over the B wire, however, are interrupted during the synchronizing period, usually from forty-four to fifty-nine minutes after the hour, by contacts 16 operated by a cam driven by the master clock, these contacts being closed during the synchronizing period and opened just before the sixtieth minute. When the contacts 16 are closed a circuit is established (through wires 11 and 12, contact 16, relay coil 17 and wire 14) causing relay coil 17 to become energized and open the normally closed relay contacts 18. The stepping impulse circuit extends from contacts 15, through wire 19, and contacts 18 to the B wire when said contacts 18 are closed.

Between the fifty-ninth and sixtieth minute, cam controlled contacts 21 are closed by the master clock for a portion of a minute and during this period, lasting slightly over half a minute, complete a circuit through contacts 22. Contacts 22 are operated by the relay coil 23, and close once every second. (The manner in which the relay coil 23 is operated will be explained in detail later). Thus, during this portion of a minute the relay coil 13 is energized repeatedly and by closing its contacts 15 supplies a series of rapid impulses to the A wire.

The secondary clocks may be of the well known ratchet and pawl type such as are shown in the patent to J. W. Bryce, #1,752,939 dated April 1, 1930, in which a magnet 25 receives the impulses and is energized therefrom to advance the clocks. Each secondary clock drives a cam 26 which opens and closes contacts 27 and 28. Prior to the beginning of the synchronizing period i. e. about thirty minutes after the hour, contacts 27 are closed and contacts 28 open thereby connecting the driving magnet 25 to the A line.

When each secondary clock moves from its fifty-eighth minute to its fifty-ninth minute indication the contacts 27 open and contacts 28 close thereby connecting the driving magnet 25 to the B line. At the next succeeding thirtyminute period after the hour the contacts 27 and 28 shift back to the position originally mentioned and as shown in the drawings.

It will be recalled that no impulses are sent over the B line during the synchronizing period and that a series of fast impulses are sent over the A line at the end of the period. As the secondary clock contacts 27 and 28 shift to connect the driving magnet 25 to the B wire when the secondary registers fifty-nine minutes after the hour it will be obvious that as all secondary clocks will receive the first stepping impulse over the B wire on the sixtieth minute as previously described. they will start on in synchronism with the master clock.

The relay coil 23 which is energized every second to close contacts 22 and thus initiate rapid impulses is controlled by the pendulum as illustrated in the preferred embodiment of the invention. As it is assumed in this instance that this contact is to close once each second, it will be assumed that a sixty beat pendulum is being used which lends itself to the simplest, most practical, and most accurate arrangement. In Fig. 1 is shown the front view of a conventional type of pendulum controlled master clock, the movement of which is generally shown at 30 having associated therewith a sixty beat pendu lum 31 to the lower end of which is fixed one plate 32 of a two plate condenser C1, the other plate 33 being mounted substantially horizontal on a bracket 34 which is fixed to the back of the clock case (not shown) on which the master clock mechanism may be mounted.

Figs. 2 and 3 show a modified form using a three plate condenser mounted in a substantially vertical plane in which the center plate is mounted on the pendulum and swings between two fixed plates 33a and 33b mounted on brackets which are fixed to the mounting board of the clock mechanism. The plate 32 therefore swings back and forth with the pendulum and in the preferred form as shown in Fig. 1 the plates 32 and 33 are slightly curved to conform with the arc of swing of the pendulum said plates being concentric with each other. The plate 32 therefore passes over the plate 33 at each swing of the pendulum and in close proximity to each other.

The stationary plate 33 is connected to the grid of one or more three element thermionic vacuum tubes 36, the number of tubes required being dependent on the desired power output. For the sake of a clear and simplified descrip tion only one tube is shown in the diagram of Fig. 4. The movable plate 32 is connected through the steel pendulum rod, suspension spring 39, wire 40, blocking condenser C2, wire 41 to one of the secondary windings 42 of a power transformer of which the primary wind 43 is connected to an alternating current source of input supply at 44. This condenser plate 33 could be connected direct instead of through a blocking condenser, but the blocking condenser C-2 of about .5 microfarad is preferred to insulate the pendulum from the comparatively high voltage of secondary coil 42 (approximately 150 volts). This is the only function of condenser C-2 and does not affect the operating characteristics of the circuit. The filament 45 of the tube is connected to the secondary winding 46 and the plate 47 is connected to the secondary coil 48, through wires 49, magnet coil 23 and wires 50 and 51.

The magnet coil 23 is shunted by a condenser 0-3 of comparatively high capacity (approximately 45 microfarads). The secondary coils 42 and 48 are also connected to the coil 46 to complete the grid and plate circuits. A resistance Rl, varying from 1 to 10 megohms depending on the type of tube to be used is connected between the grid and filament of the vacuum tube. In order to insure dependable operation over a long period of time, the power output of the vacuum tube is so chosen that normal operating characteristics of the circuit is obtained with sub-normal filament voltage (for a 5 volt tube about 3 volts), in other words about sixty percent of normal filament voltage.

indicated by curve 50 as Inasmuch as various circuits containing vacuum tubes are old and also as the three element tube is old and well known in the art, it is believed that a very brief description of the operating characteristics of such a tube insofar as 'they have a bearing on the present circuit will sufllce to make clear the description and operation of the circuit as a whole. When the filament is heated the electrons emitted therefrom are of negative polarity. If the plate is made positive with respect to the filament by proper connections of both to the power supply, then current will flow in the plate circuitif on the other hand the polarity is reversed so that the plate is the same polarity as the filament i. e. negative, then no current will flow. The plate current increases with an increase in plate potential within certain limits, however, the relation between the plate current and the plate potential is not linear or in direct ratio as it is influenced by the grid potential with respect to the filament, i. e. for any definite value of plate voltage, the plate current is also a function of the potential of the rid.

Within certain limits of positive and negative grid voltages, a definite grid voltage corresponds to a definite plate current, these limits depending upon the constructionof the tube such as the diameter of the grid wires, the spacing between the grid wires and the spacing between the plate and the grid. Let it be assumed that the positive and negative limit of this grid voltage for a given tube is plus e and minus e respectively. At a grid voltage of minus e the plate current becomes zero and any further increase of negative grid potential does not effect the plate current, it still remains zero (Fig. 6). At a grid potential of plus e the plate current has attained a maximum value which does not increase with further increase in the positive grid potential. The increase of the plate current from zero when the grid potential is minus e, its negative limit, to the point the grid potential is zero, is the maximum rate of increase and the further rate of increase of the plate current from zero grid potential to its positive limit plus e is much less. Therefore when the grid potential is zero the plate current is very nearly its maximum value.

When the primary coil 43 of the transformer is connected to a suitable sourceof alternating current supply, three secondary voltages are induced in the coils 42, 46 and 48 the value of which are determined by the relative windings of said coils. In the preferred form the voltage of coil 42 is 150 volts, of coil 46 is 3 volts, and of coil 48 is 180 volts which have a general form which is shown in Fig. 5. When the movable plate 32 is in position 31a (Fig. 4) (dotted lines) the grid potential is held at approximately zero voltage with respect to the filament by means of the grid resistance R-1 so that almost the maximum plate current is allowed to fiow as previously explained. r

The plate however is now connected to an alternating current supply and as plate current can fiow only when the plate is positive, there is a pulsating direct current flowing in the plate circuit relating to voltage characteristics shown diagrammatically in Fig. 5 and substantially consists of the bumps of the curve 50 above or on the positive side of the line 51 which is the line of 'zerovoltage or amplitude. The negative bumps belowthe line are eliminated. A condenser 97-3- is shunted across the relay coil 23 and this becomes charged during these bumps and delivers a somewhat smoother voltage substantially as diagrammatically indicated by the curve 52 in Fig. 5. No attempt has been made in the diagram to show the proper phase relation between the curves 50 and 52. I

When the movable condenser plate 32 is in the position as shown by pendulum 31 (Fig. 4) in which said plate is directly adjacent its cooperating fixed plate 33, a voltage is impressed on the grid. The phase relation between the grid winding 42 and the plate winding 48 is so chosen and accomplished by suitable winding, that when the plate is positive the grid is negative and vice versa. If during the time that the plate is positi ve, the grid is of -a negative potential greater] than minus e (Fig. 6) which is the case in the present arrangement, it is clear that no current can flow. When the grid during the next alternation becomes positive it would ordinarily permit plate current to flow, but the plate potential has also reversed so that still no plate current can fiow for reasons already explained. It will thus be seen that under no condition can plate current flow when condenser C1 is in the position indicated 31 in Fig. 4 or as shown in Fig. 1.

The purpose of R-l is to provide a path for the negative charge on the grid to the filament when the movable plate condenser moves from the extreme swing of the pendulum through its vertical position. It will be seen when the pendulum is at either extreme of its swing the current will flow in the plate circuit and as the pendulum passes through its vertical position so that the plates of C-1 are superimposed, said plate current will be interrupted, thus the plate current will fiow intermittently in synchronism with the motion of the pendulum and will energize the magnet coil 23 intermittently to cause contacts 22 to initiate seconds beat impulses in synchronism with the swing of the pendulum.

Although the invention as shown is in connection with the operation of a relay it can be readily understood that any magnetic device such as a seconds beat clock could be operated directly from the plate current.

While the fundamental novel features of the invention as applied to a single modification has been pointed out it will be understood that various omissions and substitutions and changes in the form and details of the device illustratedv 125 and in its operation may be made by those skilled in the art without departing from the spirit of the invention. I intend therefore to be limited only as indicated by the scope of the following claims.

I claim: a

1. In a secondary clock system of the electric impulse type, in combination with a master clock, secondary clocks and circuits connecting the same, of a space discharge device having an input and out-put circuit adapted to transmit electrical impulses to said secondary clocks, an oscillating member in said master clock, a-condenser for varying the capacity of said in-put circuit, an element of said condenser being rigidly attached to said oscillating member and another element being fixed adjacent the path of oscillation of said first mentioned member.

2. In a secondary clock system of the electric impulse type, in combination with a master clock, secondary clocks and circuits connecting the same, of a space discharge device having an input and an out-put circuit adapted to transmit electrical impulses to said secondary clocks, a

master clock having a constant period oi oscillation for regulating the escapement of said clock works, a condenser for varying the capacity of said in-put circuit, an element of said condenser 5 rigidly attached to said pendulum whereby said element oscillates with said pendulum, and an- 

